Many of the Alfa Racers use a small Japanese one that is OE on fork lift trucks but it may not be powerful enough for night driving. I use a regular Bosch from an S3 Spider but I have a small crank pulley from Gordon Raymond that reduces the speed of both the alternator and the water pump. That makes pump cavitation less likely and reduces the stress on the alternator at high rpm and probably reduces the power consumption of them.
85 GTV6 3L
76 Suzuki GT500
A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke